There are a variety of different industries in which deliquefying systems are employed. In many of those industries, a vacuum dewatering system is used to remove liquid, such as water, from a liquid/particle mixture. This has proven to be an effective way to remove a desired percentage of water from many different types of materials. It has been particularly useful in the papermaking industry where water is removed from pulp. Vacuum dewatering tables of many types and kinds have been devised over the years and continuous improvements are still being made.
Conventionally, the wet web of material is positioned on a forming fabric such as a Fourdrinier wire and that combination is passed continuously over a vacuum table which employs many different types of dewatering mechanisms. Suction pipes and vacuum boxes are common structures and they employ appropriate wear surfaces over which the combination of wire and wet material is passed. To enhance the dewatering aspects of the system, many types of blades or foils are used on the wear surfaces to increase the efficiency of the dewatering operation. These structures can be used independently or in combination with a vacuum source.
A difficulty that is often encountered in the common type of arrangement with the wire passing over the arrangement of vacuum dewatering mechanisms involves the sealing of the end zones. This is the area at the transverse edges of the wire and the drainage devices. It is desirable to have the vacuum mechanisms pull air through the material on the wire thus drawing water from the wet web of material. Vacuum is lost when air can leak in the end zones between the wire and the drainage device. This air does not assist in the dewatering procedure and in fact detracts from it since less water is then drawn through the wire and wet web of material. Accordingly, various types of end seals have been developed over the years and they primarily take the form of solid types of end deckles which are structures employed to plug the end zones and avoid the leakage problem. There are many types of solid end deckles that have been provided through the years and which have been adapted according to the types of drainage devices employed and the material being deliquefied. However, the overall concept has been to employ a rigid type of plug to close the end zones and eliminate the leakage of air at that point thus adding to the efficiency and operation of the system. For example, U.S. Pat. No. 3,836,428 shows appropriate solid end deckles to seal end zones of a suction box arrangement commonly used in the papermaking industry.
No attempts have been made to seal the end zones by fluid means. Fluid such as gases and liquids have been used for other purposes such as edge trimming and restricting the flow of a material in the transverse direction. Application of this general concept is readily apparent from U.S. Pat. Nos. 1,746,434; 2,709,398; 3,075,579; 3,361,620; 3,405,031; 3,607,624; and 3,839,148. However all of the art concerns deckle trimming and does not consider the concept of utilizing a liquid deckle as a seal to prevent air leakage in the end zone of machinery in the papermaking industry or any similar equipment used for deliquefication under the influence of vacuum.
It would certainly be advantageous to be able to employ the advantages of fluids in sealing the end zones in lieu of a solid deckle as a further improvement in the development of deliquefying systems in general and, in particular, dewatering systems for the papermaking industry.